Messages in this thread | | | Date | Thu, 23 Jun 2022 16:34:40 +0800 | From | Shuai Xue <> | Subject | Re: [PATCH v1 1/3] docs: perf: Add description for Alibaba's T-Head PMU driver |
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在 2022/6/20 PM7:49, Jonathan Cameron 写道: > On Fri, 17 Jun 2022 19:18:23 +0800 > Shuai Xue <xueshuai@linux.alibaba.com> wrote: > >> Alibaba's T-Head SoC implements uncore PMU for performance and functional >> debugging to facilitate system maintenance. Document it to provide guidance >> on how to use it. >> >> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com> > > Hi Shuia Xue, > > A few quick comments inline, > > Thanks, > > Jonathan
Hi, Jonathan,
Thank you very much for your quick comments.
> >> --- >> .../admin-guide/perf/alibaba_pmu.rst | 94 +++++++++++++++++++ >> Documentation/admin-guide/perf/index.rst | 1 + >> 2 files changed, 95 insertions(+) >> create mode 100644 Documentation/admin-guide/perf/alibaba_pmu.rst >> >> diff --git a/Documentation/admin-guide/perf/alibaba_pmu.rst b/Documentation/admin-guide/perf/alibaba_pmu.rst >> new file mode 100644 >> index 000000000000..337f4f1d4c54 >> --- /dev/null >> +++ b/Documentation/admin-guide/perf/alibaba_pmu.rst >> @@ -0,0 +1,94 @@ >> +============================================================= >> +Alibaba's T-Head SoC Uncore Performance Monitoring Unit (PMU) >> +============================================================= >> + >> +The Yitian 710, custom-built by Alibaba Group's chip development business, >> +T-Head, implements uncore PMU for performance and functional debugging to >> +facilitate system maintenance. >> + >> +DDR Sub-System Driveway (DRW) PMU Driver >> +========================================= >> + >> +The Yitian 710 SoC supports the most advanced DDR5/4 DRAM to provide >> +tremendous memory bandwidth for cloud computing and HPC. The Driveway is a >> +module which is a bridge between a router of mesh network and memory >> +controller. It provides various functions like secure control, address map >> +and so on. > > I'd focus on the PMU aspect. No point in describing other features in this > document.
Got it. I will delete this in next version.
>> + >> +Yitian 710 employs eight DDR5/4 channels, four on each die. Each channel is >> +independent of others to service system memory requests. And one DDR5 > > Each DDR5 channel...
Good catch, I will declare as DDR5 channel.
> >> +channel is split into two independent sub-channels. The DDR Sub-System >> +Driveway implements separate PMUs for each sub-channel to monitor various >> +performance metrics. >> + >> +The Driveway PMU devices are named as ali_drw_<sys_base_addr> with perf. >> +For example, ali_drw_21000 and ali_drw_21080 are two PMU devices for two >> +sub-channels of the same channel in die 0. And the PMU device of die 1 is >> +prefixed with ali_drw_400XXXXX, e.g. ali_drw_40021000. >> + >> +Each sub-channel has 36 PMU counters in total, which is classified into >> +four groups: >> + >> +- Group 0: PMU Cycle Counter. This group has one pair of counters >> + pmu_cycle_cnt_low and pmu_cycle_cnt_high, that is used as the cycle count >> + based on DDRC core clock. >> + >> +- Group 1: PMU Bandwidth Counters. This group has 8 counters that are used >> + to count the total access number of either the eight bank groups in a >> + selected rank, or four ranks separately in the first 4 counters. The base >> + transfer unit is 64B. >> + >> +- Group 2: PMU Retry Counters. This group has 10 counters, that intend to >> + count the total retry number of each type of uncorrectable error. >> + >> +- Group 3: PMU Common Counters. This group has 16 counters, that are used >> + to count the common events. >> + >> +For now, the Driveway PMU driver only uses counters in group 0 and group 3. >> + >> +Example usage of counting memory data bandwidth:: >> + >> + perf stat \ >> + -e ali_drw_21000/perf_hif_wr/ \ > > What does hif stand for? Also, perf seems redundant for > a perf event.
HIF stands for Host Interface which is a Synopsys’ custom-defined interface. On the host side, there is a choice of an AMBA 4 AXI interface or a custom Host Interface (HIF). The AMBA interface supports single or multi-port configurations, while the HIF supports a single port only. Read, write, and RMW requests as well as write data are received through the HIF. I will doc this in next version.
The `perf` prefix means Performance Logging Signals in DDRC, I will remove it in next version.
>> + -e ali_drw_21000/perf_hif_rd/ \ >> + -e ali_drw_21000/perf_hif_rmw/ \ >> + -e ali_drw_21000/perf_cycle/ \ >> + -e ali_drw_21080/perf_hif_wr/ \ >> + -e ali_drw_21080/perf_hif_rd/ \ >> + -e ali_drw_21080/perf_hif_rmw/ \ >> + -e ali_drw_21080/perf_cycle/ \ >> + -e ali_drw_23000/perf_hif_wr/ \ >> + -e ali_drw_23000/perf_hif_rd/ \ >> + -e ali_drw_23000/perf_hif_rmw/ \ >> + -e ali_drw_23000/perf_cycle/ \ >> + -e ali_drw_23080/perf_hif_wr/ \ >> + -e ali_drw_23080/perf_hif_rd/ \ >> + -e ali_drw_23080/perf_hif_rmw/ \ >> + -e ali_drw_23080/perf_cycle/ \ >> + -e ali_drw_25000/perf_hif_wr/ \ >> + -e ali_drw_25000/perf_hif_rd/ \ >> + -e ali_drw_25000/perf_hif_rmw/ \ >> + -e ali_drw_25000/perf_cycle/ \ >> + -e ali_drw_25080/perf_hif_wr/ \ >> + -e ali_drw_25080/perf_hif_rd/ \ >> + -e ali_drw_25080/perf_hif_rmw/ \ >> + -e ali_drw_25080/perf_cycle/ \ >> + -e ali_drw_27000/perf_hif_wr/ \ >> + -e ali_drw_27000/perf_hif_rd/ \ >> + -e ali_drw_27000/perf_hif_rmw/ \ >> + -e ali_drw_27000/perf_cycle/ \ >> + -e ali_drw_27080/perf_hif_wr/ \ >> + -e ali_drw_27080/perf_hif_rd/ \ >> + -e ali_drw_27080/perf_hif_rmw/ \ >> + -e ali_drw_27080/perf_cycle/ -- sleep 10 >> + >> +The average DRAM bandwidth can be calculated as follows: >> + >> +- Read Bandwidth = perf_hif_rd * DDRC_WIDTH * DDRC_Freq / DDRC_Cycle >> +- Write Bandwidth = (perf_hif_wr + perf_hif_rmw) * DDRC_WIDTH * DDRC_Freq / DDRC_Cycle >> + >> +Here, DDRC_WIDTH = 64 bytes. >> + >> +The current driver does not support sampling. So "perf record" is >> +unsupported. Also attach to a task is unsupported as the events are all >> +uncore. >> diff --git a/Documentation/admin-guide/perf/index.rst b/Documentation/admin-guide/perf/index.rst >> index 69b23f087c05..bf466ae91c6c 100644 >> --- a/Documentation/admin-guide/perf/index.rst >> +++ b/Documentation/admin-guide/perf/index.rst >> @@ -17,3 +17,4 @@ Performance monitor support >> xgene-pmu >> arm_dsu_pmu >> thunderx2-pmu >> + thead_pmu
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